The present invention relates to explosive projectiles and, in particular, to a safety mechanism for preventing premature ignition of a charge carried by the projectile.
Such a projectile is disclosed in U.S. Pat. No. 5,159,150 and comprises a body that is to be fired from a launcher tube (barrel) by means of an expulsion charge. An acceleration sensor moves from a safety position to an armed position upon acceleration of the body as a result of its inertia of mass against the direction of launch. A barrel probe is movable in a direction perpendicular to the launch by a pyrotechnical time delay element from a safety position to an armed position wherein an end thereof extends laterally beyond the body covering. The barrel probe is normally held in its safety position by engagement with the barrel, wherein the barrel probe blocks the movement of a firing pin against a percussion cap that acts upon the active charge. The barrel probe is fixed in the safety position by the acceleration sensor when the latter is in its safety position (i.e., when the body is located in the launcher tube). The firing pin can only contact the percussion cap when the acceleration sensor and the barrel probe are simultaneously in their armed positions. In that event, the firing pin is moved toward the percussion cap by the propulsion gas of a second pyrotechnical delay element. Thus, both the firing pin and the barrel probe are acted upon by respective pyrotechnical delay elements.
Although that device has proven itself, room for improvement remains. For instance, in order to ensure proper operation of the device, it is necessary that the delay times of the two pyrotechnical delay elements be synchronized, or tuned. That requirement has caused difficulties in many applications. In addition, the use of two pyrotechnical delay elements requires that the projectile be constructed in a way that can lead, in particular, to weight and space problems which are especially undesirable, primarily when firing projectiles from an aircraft or similar vehicle.
On the other hand, it is already known how to actuate a barrel probe and a firing pin without the use of a corresponding pyrotechnical delay element, whereby the use of a pyrotechnical delay element is only envisioned to define the ignition time of the active charge. In the process, however, there can arise problems with regard to handling safety, because, when the acceleration sensor, for example, is freed by an impact, an ignition of the active charge cannot be ruled out, even though projectile has not exited the launcher tube.
This invention has as an object the improvement of the afore-described type of safety device, so that with little weight and simple construction the post-firing safety function can be improved, and increased pre-firing safety can be attained to facilitate handling of the projectile in the laboratory and during work with duds.